Fluid flow control devices

ABSTRACT

A fluid flow control device having first and second valve means biassed normally towards closed positions, and control means. The control means is operable, when the device is connected in a fluid flow path, either to displace the first valve means against its bias into an open position to permit fluid to flow through the device from an inlet side to an outlet side thereof, or to displace the second valve means against its bias into an open position to vent the outlet side of the device. The second valve means is also openable independently of the control means under the action of excess pressure on the outlet side of the device to relieve this excess pressure.

United States Patent 1191 Jan. 8, 1974 Kirkman [54] FLUID FLOW CONTROL DEVICES 3,207,183 9/1965 Stuhl l37/636.l X [75] Inf/6mm; gi g zz g gfg gfi Primary Examiner-Henry T. Klinksiek Assistant Examiner-Robert J. Miller [73] Assignee: I. V. Pressure Controllers Limited, Atl0rney-R0bert B. Larson et a].

Feltham, Middlesex, England 22 Filed: Apr. 26, 1972 [57] ABSTRACT A fluid flow control device having first and second [21] Appl' 247744 valve means biassed normally towards closed positions, and control means. The control means is opera- [30] Foreign Application Priority Data ble, when the device is connected in a fluid flow path, Dec. 15, 1971 Great Britain 58,300/71 either to displace the first valve means against its bias into an open position to permit fluid to flow through 52 US. Cl. 137/596.2, 137/636.1 the device from an inlet side to an outlet side thereof, 1 51 1111. C1. F16]: 31/00 or to displace the Second valve means against its bias [58] Field Of Search 137/636, 596.2, 636.1 into an p position to vent the outlet side of the vice. The second valve means is also openable inde- 56] References Ci d pendently of the control means under the action of ex- UNITED STATES PATENTS cess pressure on the outlet side of the device to relieve 2,054,346 9/1936 Van Sittert 137 5962 excess'pressure' 2,376,322 5 1945 Benaway 1371636.] 8 Claims, 1 Drawing Figure FLUID FLOW CONTROL DEVICES BACKGROUND OF THE INVENTION This invention relates to fluid flow control devices for connection in a fluid flow path, and concerns in particular such a device which will function as a control valve for use in inflating and deflating inflatable bags used for lifting applications such as for lifting crashed vehicles for rescue purposes.

SUMMARY OF THE INVENTION In accordance with the present invention there is provided a fluid flow control device for connection in a fluid flow path, said device having a first valve means and a second valve means both normally biassed towards closed positions, and control means which, when the device is connected as aforesaid, is operable in one control action to displace the first valve means against the bias into an open position to permit fluid flow through the device from an inlet side to an outlet side thereof, and is operable in another control action to displace the second valve means against the bias into an open position to vent the outlet side of the device, said second valve means being arranged also to be openable independently of said control means under the action of excess pressure on said outlet side thereby to relieve said excess pressure.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made, by way of example to the accompanying single figure drawing which illustrates diagrammatically in part section, a fluid flow control device according to one embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT A fluid flow control device of the invention as shown in the drawing, has a housing 1 containing a first valve means 2 and a second valve means 3, with both valve means 2, 3 being normally biassed towards closed positions in any convenient manner such as by respective springs 4, 5. The two valve means 2, 3 are both of similar construction as shown although they can of course be of different construction if desired. The valve means 2 has a valve member with a stem portion 6 and an enlarged head portion 7 reciprocally mounted in a chamber 8 together with the spring 4. Similarly the valve means 3 has a valve member with a stem portion 9 and an enlarged head portion 10 reciprocally mounted in a chamber 1 1 together with the spring 5. Each head portion 7, 10 is provided with sea] means, such as a soft annular disc 12, 13 forming a facing on the leading end of the head portion 7, 10 respectively. The disc 12 cooperates with a valve seat 14, provided around the mouth of a passage leading into the valve means containing chamber 8, when the valve means head portion 7 is spring biassed towards the closed position. Similarly the disc 13 cooperates with a valve seat 15 provided around the mouth of a passage leading into chamber 1 l.

The fluid flow control device also includes control means which, when the device is connected in a fluid flow path, is operable in one control action to-displace the first valve means 2 against its bias into an open position to permit fluid flow through the device from an inlet 16 to an outlet 17 thereof, and is operable in another control action to displace the second valve means 3 against its bias into an open position to vent the outlet 17 of the device. To this end the two valve means 2, 3 are conveniently arranged on the same axis of reciprocation but on opposite sides of a third chamber 18, with the passages of the first two chambers 4, 11 opening into said third chamber 18. The two passages are concentric with said axis of reciprocation and displacement means such as a push rod 19 is located on said axis of reciprocation with one rod end projecting through the appropriate passage and slidably engaging in a recess or bore 20 provided in the head and stem portions 7, 6 of the first valve means 2, and with the other rod end similarly projecting through the other passage and slidably engaging in a similar recess or bore 21 in the head and stem portions 10, 9 of the second valve means 3. In the closed positions of the two valve means 2, 3, that is to say in the neutral position, the push rod ends engage stop means provided in the bores 20, 21 such as the blind ends of these bores.

Axial displacement of the push rod 19 in either direction along the axis of reciprocation mechanically opens one or other of the two valve means 2, 3. For this purpose the push rod 19 is provided with two spaced apart collars 22, 23 intermediate its ends and a cam 24 is located between the two collars 22, 23 in engagement therewith. This cam 24 in this case is an eccentric end portion of a shaft 25 rotationally mounted in the housing 1 to extend perpendicular to the push rod 19. The shaft end opposite to the cam 24 projects out of the housing 1 and carries a control handle 26 secured to the shaft. Movement of the control handle 26 to one side or the other of the neutral position causes the shaft 25 to rotate in one or the other direction so that the cam 24 displaces the push-rod 19 one way or the other to open the appropriate valve means 2 or 3 mechanically by displacing its head portion 7 or 10 clear of the cooperating valve seat 14 or 15, against the spring bias 4 or 5; The fluid flow outlet 17 from the device opens from the third chamber 18 and the fluid flow inlet 16 opens into the chamber 8 containing the first valve means 2. More than one such inlet or outlet can be provided in the respective chambers if desired. When the first valve means 2 is held in the open position by the displaced push rod 19 fluid flows from the inlet 16 through the first valve means chamber 8 and passage, into the third chamber 18 and out of the outlet 17. Similarly when the second valve means 3 is held in the open position by the displaced pushrod l9 fluid is vented from the outlet 17 through the third chamber 18, through the passage of the open second valve means 3 and into the second valve means chamber 11, whilst the first valve means 2 is in the closed position. The second valve means chamber 11 is provided with openings (not shown) communicating with atmosphere or with any other convenient return or exhaust means for returning or exhausting the fluid vented from the outlet 17 through the open second valve means 3.

Furthermore the second valve means 3 is also arranged to be openable independently of the control handle 26, when the fluid flow control device is operatively connected in a fluid flow line, under the action of excess pressure at the outlet 17 of the device thereby to relieve this excess pressure. To this end the head portion 10 of the second valve means 3 and its cooperating valve seat 15 and passage are so dimensioned and the second valve means spring 5 so calibrated that the pressure acting, through the second valve means passage from the outlet 17, on the head portion 10, will, at a certain excess pressure, displace the valve head portion away from its seat against the biassing spring force, to relieve this excess pressure. When the pressure has fallen to an acceptable lower level the force exterted by the fluid on the head portion 10 is less than the biassing force of the spring 5 and the spring 5 then urges the second valve means 3 once again into the closed position.

Means may be provided for varying the biassing force of the springs 4, 5 such as for instance a screw cap 27 bearing on one end of the spring 5. The construction of the fluid flow control device may be such that the valve seats form part of the housing 1 or are inserts therein.

A typical use of a fluid flow control device of the invention is for controlling the inflation and deflation of inflatable bags. Inflatable bags made conveniently of rubber are used for numerous lifting applications such as for lifting overturned vehicles from trapped people. For example a 6 inch high deflated bag of for instance three foot diameter can be inserted under a load and inflated to a height of for example 2% feet in under a minute. Groups of two or three such bags provide .a ready means of lifting overturned vehicles from trapped people.

To inflatesuch a bag it is necessary to control a supply of fluid such as compressed gas, or air, or liquid under pressure to the bag. The source of the gas is usually, although not essentially, a cylinder of compressed air. A reducing valve would reduce the pressure from the high cylinder pressure (approximately 2000 p.s.i.g.) to a supply pressure suitable for a control valve for the bag. The bags are designed to operate at low pressure in the region of 2 to p.s.i.g. and if the reducing valve is set to pass gas at this pressure to the bag control valve unacceptably slow filling of the bag results. However the use of a fluid flow control deviceof the invention as thebag control valve enables the pressure of gas supplied to the control device to be increased to a value of say p.s.i.g.

Thus a control device of the invention is connected in the fluid flow line between the reducing valve and the bag. Turning the control handle 26 of the device to one side of the neutral position actuates the push rod 19 and opens the first valve means 2 so that gas flows through the device from inlet 16 to outlet 17 into the bag.

The second valve means 3 acts as a pressure relief valve to protect the bag. This latter valve means 3 is set to relieve the outlet pressure at some pressure, say 5 p.s.i.g, which is within the safe working limit of the bag, thus protecting against the application of the full pressure supplied to the control device (say 30 p.s.i.g.) or over-pressurisation due to movement of a load on the bag. Movement of the control handle 26 on the other side of the neutral position in the opposite directon to that previously moves the push rod 19 in the opposite direction, allowing the first valve means 2 to close and cut off the pressure supply from the source, and opens the second valve means 3 mechanically. This vents the bag and permits lowering of a load thereon.

A friction pad 27 is optionally incorporated in the fluid flow control device of the invention between the housing 1 and the control handle 26 so that the control handle 26 may be set at any desired position, and thereby the valve means, to facilitate control of two or three bags at the same time. Alternatively if the friction pad 27 is omitted the biassing springs 45 will act to return the control handle 26 to the neutral position in which the valve means are closed mechnaically, so as to afford the so-called Dead Mans Handle control.

A fluid flow control device of the invention has a large relief area which is necessary at the low utilisation pressures and big volumes contemplated.

I claim:

1. A fluid flow control device for connection in a fluid flow path, said device having a housing; an inlet to the housing; an outlet from the housing; a vent from the housing; a first valve member in the housing normally biassed towards a closed position and openable to permit fluid flow through the device from the inlet to the outlet; a second valve member in the housing normally biassed towards a closed position and openable to place the outlet in communication with the vent; a push rod common to the first and second valve members and slidably mounting the valve members for movement on a common axis; and a control member en-gaged with the push rod for selectively moving the push rod from a neutral position in which each valve member can adopt its closed position either to open the first valve member against its associated bias thereby to permit fluid flow through the device from the inlet to the outlet, or to open the second valve member against its associated bias thereby to place the outlet in communication with the vent; the push rod being disposed in a chamber in the housing that is open only to the outlet when the valve members are closed so that, in use, the push rod is disposed in the fluid passing to the outlet; and the bias applied to the second valve member being selected such that this second valve member opens independently of movement of the push rod under the action of excess pressure at the outlet thereby to place the outlet in communication with the vent and thus relieve the excess pressure.

2. A fluid flow control device according to claim 1 wherein each valve member has a stem portion and an enlarged head portion reciprocally mounted in an associated chamber in the housing, the head portion of the associated valve member cooperating with said valve seat.

3. A fluid flow control device according to claim 2 wherein valve means bias is provided by a spring mounted in the valve means chamber.

4. A fluid flow control device according to claim 3, wherein the valve member head portion includes seal means for cooperation with the valve seat.

5. A fluid flow control device according toclaim 4 wherein the seal means is a soft annular disc forming a facing on the leading end of the valve member head portion.

6. A fluid flow control device according to claim 1 wherein the push rod has two spaced apart collars intermediate its ends and wherein the control handle is connected to a shaft rotationally mounted in the housing and provided at its free end with an eccentric cam portion for engaging the collars, to displace the push rod.

7. A fluid flow control device according to claim 6 wherein friction means is provided between the housing and the control handle to enable the handle to be set in desired positions.

8. A fluid flow control device according to claim 7 wherein the second valve means is so dimensioned and its bias spring so calibrated to enable the second valve means to open independently of the control means. 

1. A fluid flow control device for connection in a fluid flow path, said device having a housing; an inlet to the housing; an outlet from the housing; a vent from the housing; a first valve member in the housing normally biassed towards a closed position and openable to permit fluid flow through the device from the inlet to the outlet; a second valve member in the housing normally biassed towards a closed position and openable to place the outlet in communication with the vent; a push rod common to the first and second valve members and slidably mounting the valve members for movement on a common axis; and a control member en-gaged with the push rod for selectively moving the push rod from a neutral position in which each valve member can adopt its closed position either to open the first valve member against its associated bias thereby to permit fluid flow through the device from the inlet to the outlet, or to open the second valve member against its associated bias thereby to place the outlet in communication with the vent; the push rod being disposed in a chamber in the housing that is open only to the outlet when the valve members are closed so that, in use, the push rod is disposed in the fluid passing to the outlet; and the bias applied to the second valve member being selected such that this second valve member opens independently of movement of the push rod under the action of excess pressure at the outlet thereby to place the outlet in communication with the vent and thus relieve the excess pressure.
 2. A fluid flow control device according to claim 1 wherein each valve member has a stem portion and an enlarged head portion reciprocally mounted in an associated chamber in the housing, the head portion of the associated valve member cooperating with said valve seat.
 3. A fluid flow control device according to claim 2 wherein valve means bias is provided by a spring mounted in the valve means chamber.
 4. A fluid flow control device according to claim 3, wherein the valve member head portion includes seal means for cooperation with the valve seat.
 5. A fluid flow control device according to claim 4 wherein the seal means is a soft annular disc forming a facing on the leading end of the valve member head portion.
 6. A fluid flow control device according to claim 1 wherein the push rod has two spaced apart collars intermediate its ends and wherein the control handle is connected to a shaft rotationally mounted in the housing and provided at its free end with an eccentric cam portion for engaging the collars, to displace the push rod.
 7. A fluid flow control device according to claim 6 wherein friction means is provided between the housing and the control handle to enable the handle to be set in desired positions.
 8. A fluid flow control device according to claim 7 wherein the second valve means is so dimensioned and its bias spring so calibrated to enable the second valve means to open independently of the control means. 